If you are installing SharePoint and you bump into the issue that ASP Net v2.0 is not in the Web Server Extensions, then you could do a research and find out that you installed a newer version of the framework, namely SP1.

According to Microsoft, you need to uninstall SP1, install .Net 2.0 and then move from there: http://support.microsoft.com/default.aspx/KB/906894

Sounds a bit dumb

But don’t worry, go to
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727> or C:\WINDOWS\Microsoft.NET\Framework64\v2.0.50727> for 64 bit

Type aspnet_regiis.exe –i

A lot easier!